Multiple Myeloma vs Monoclonal Gammopathy of Undetermined Significance

Why Autologous stem cell transplant is correct

• Autologous stem cell transplant (ASCT) after induction chemotherapy remains the standard of care for transplant-eligible multiple myeloma (MM) patients (generally under age 70-75 with adequate performance status (PS) and organ function)
• ASCT prolongs progression-free survival (PFS) and likely overall survival (OS) compared to chemotherapy alone

Why the others are wrong

• A) Switch to bortezomib-based induction — this patient achieved a very good partial response (VGPR) on current induction; proceeding to ASCT is the next appropriate step, not switching induction regimens
• B) Continue lenalidomide and dexamethasone — continuing induction without proceeding to ASCT misses the opportunity for the survival benefit of transplant in an eligible patient
• D) Allogeneic stem cell transplant — not standard of care in MM due to high transplant-related mortality; autologous is preferred

Additional high-yield points

• Lenalidomide maintenance post-ASCT (CALGB 100104 trial) significantly improves PFS and OS
• Daratumumab-based quadruplet induction (Dara-VRd) is now preferred in many centers for transplant-eligible MM (PERSEUS trial)
• Minimal residual disease (MRD) negativity is the strongest predictor of long-term outcomes
• Early vs delayed ASCT: both are equally effective — some centers delay ASCT to second-line therapy

Why Serum free light chain ratio assay is correct

• The IMWG/Mayo workup of a newly detected monoclonal gammopathy pairs SPEP with immunofixation and a serum free light chain assay; the kappa/lambda ratio is one of the three Mayo risk-stratification factors (M-protein >=1.5 g/dL, non-IgG isotype, abnormal FLC ratio).
• This patient has a low-burden IgG kappa M-protein (<3 g/dL) with normal CBC, calcium, and creatinine and no immunoparesis, consistent with MGUS; an abnormal FLC ratio would raise his progression risk and intensify surveillance, so it is the appropriate next step before any invasive or imaging study.

Why the others are wrong

• Bone marrow aspiration and biopsy is reserved for higher-risk features (M-protein >=1.5 g/dL, non-IgG isotype, abnormal FLC ratio, or unexplained cytopenias); ordering it before the FLC result in a low-burden IgG case is premature and out of sequence.
• Whole-body skeletal survey x-rays are outdated; plain-film surveys have been replaced by whole-body low-dose CT, MRI, or PET-CT, and advanced imaging is reserved for intermediate/high-risk, IgA, or light-chain disease, not routine low-risk stratification.
• Congo red stain of fat pad aspirate tests for AL amyloidosis, which is suggested by cardiac, renal, or neuropathic involvement; this asymptomatic patient with normal organ function has no features prompting an amyloid biopsy.